As ultraviolet curing silicone release treating agents, a cationically polymerizable ultraviolet curing silicone release treating agent that cures by cationic polymerization (cationic polymerization type ultraviolet curing silicone release treating agent), a radically polymerizable ultraviolet curing silicone release treating agent that cures by radical polymerization, a radically addition-polymerizable ultraviolet curing silicone release treating agent that cures by radical addition polymerization, a hydrosilylation reactive ultraviolet curing silicone release treating agent that cures by hydrosilylation reaction, and the like are utilized. In such ultraviolet curing silicone release treating agents, the cationically polymerizable ultraviolet curing silicone release treating agent exhibits small volume shrinkage after curing as compared with the radically polymerizable ultraviolet curing silicone release treating agent, the radically addition-polymerizable ultraviolet curing silicone release treating agent and the hydrosilylation reactive ultraviolet curing silicone release treating agent. It is therefore said that a release treating agent layer by the cationically polymerizable ultraviolet curing silicone release treating agent has good adhesion to a substrate (see JP-A-2001-226592 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”)). However, there was the case that the release treating agent layer by the cationically polymerizable ultraviolet curing silicone release treating agent may not have sufficient adhesion to a substrate, depending on a material or structure of the substrate in the release-treated substrate, a coating thickness of the cationically polymerizable ultraviolet curing silicone release treating agent, and the like.
Further, even though there is no problem in the use under general mild environments, in the case that a release-treated substrate alone or a release-treated substrate having a pressure-sensitive adhesive layer adhered thereto is exposed under excessive heating or humidifying conditions, or is stored over a long period of time, a silicone component in the release treating agent layer drops out of the substrate. For example, in the case that the release-treated substrate is adhered to a pressure-sensitive adhesive layer, there was the case of remaining on a surface of the pressure-sensitive adhesive layer, thereby greatly hindering pressure-sensitive adhesive properties. For this reason, it is desired that the release treating agent layer by the cationically polymerizable ultraviolet curing silicone release treating agent is sufficiently adhered to a substrate of the release-treated substrate in order to maintain release properties of the release-treated substrate and pressure-sensitive adhesive properties of a pressure-sensitive adhesive tape or sheet in a stable state.